We propose to expand and maintain the Adult to Adult Living Donor Liver Transplantation Cohort Study Data Coordinating Center (A2ALL DCC) that will support a consortium of transplant centers in conducting continued observational and interventional research in living donor liver transplantation (LDLT) so as to facilitate understanding of the short and long-term medical and health-related quality of life outcomes of transplantation on living individuals who have donated a liver lobe as well as those who are candidates for and/or recipients of LDLT procedures. In addition, we will gain insight into liver regeneration and other biological processes through study of this unique procedure. The proposed DCC consists of the original A2ALL DCC team of collaborating experts in the fields of live organ donor transplantation, hepatology, clinical research design, database management, and research involving linkages of large public and private electronic health care databases. The DCC will continue to support the project, including research coordination, communications and logistics, study design, centralized data management, and analytical expertise. The specific scientific aims of the DCC will be developed in collaboration with the A2ALL Steering Committee. Proposed scientific activities include: 1) determination of long-term LDLT donor outcomes, including health-related quality of life, 2) protocols for immunosuppression minimization in the LDLT setting, 3) continued focus on hepatitis C and hepatocellular carcinoma, 4) identification of recipient and donor characteristics that are most favorable for LDLT, and 5) evaluation of newer approaches to LDLT to improve donor and recipient outcomes.